Near Field Communications (NFC) is a short-range wireless communications technology standard that relies on inductive coupling of two devices to transfer information over a short range of 10 centimeters (approximately 4 inches) or less. Recent years have witnessed growing usage of NFC technology in smart phones, key fobs, credit cards, and other devices, not only because of its high convenience and low cost, but also because its extremely short range makes it resistant to interception. For example, this technology has been used to enable users to unlock their phones by touching it with an NFC tag.
One problem the present inventors have recognized with this unlocking functionality is that it entails repeated polling (generation of magnetic field patterns) for reading two or more different types of NFC tags. In particular, the conventional polling process, initiated in response to turning on the phone, entails waking up a processor, which in turn causes generation of a magnetic field pattern for reading two or more types of NEC tags. If a tag is not found and confirmed to be authentic—to have the correct embedded code—the processor repeats the polling until the phone is turned off, or the tag is confirmed to be authentic. If the tag is confirmed authentic, the processor not only activates or unlocks the phone, but also regularly repeats the same polling procedure initially used to discover and authenticate the tag to confirm that the phone should remain unlocked. Unfortunately, the repeated polling in this manner to discover and re-authenticate consumes significant battery power and thus reduces battery life.
Accordingly, the present inventors have identified a need for more efficient methods of operating NFC-enabled devices.